There are the following reports on pharmaceutical compositions containing an insulin sensitizer such as a thiazolidinedione compound and the like and a biguanide.    1) A pharmaceutical agent, which contains an insulin sensitizer in combination with at least one member from an α-glucosidase inhibitor, an aldose reductase inhibitor, a biguanide, a statin compound, a squalene synthesis inhibitor, a fibrate compound, an LDL catabolism enhancer and an angiotensin converting enzyme inhibitor, is reported (see, EP-749751 A).    2) A pharmaceutical composition, which contains an insulin sensitizer, a biguanide antihyperglycaemic agent and a pharmaceutically acceptable carrier, is reported (see, WO98/57634).    3) A pharmaceutical composition, which contains thiazolidinedione, metformin hydrochloride and a pharmaceutically acceptable carrier, wherein thiazolidinedione is formulated on the surface of metformin hydrochloride, is reported (see, WO01/35940).    4) A pharmaceutical composition, which contains thiazolidinedione, metformin hydrochloride and a pharmaceutically acceptable carrier, wherein thiazolidinedione and metformin hydrochloride are respectively dispersed in pharmaceutically acceptable carriers of their own (see, WO01/35941).    5) A core formulation, which comprises (a) a first layer containing pioglitazone hydrochloride or a pharmaceutically acceptable salt thereof as an active ingredient, and (b) a core containing a biguanide as an active ingredient, wherein at least a part of the core is enclosed by said first layer, is reported (see, WO01/82875).    6) A core formulation, which comprises a first layer containing pioglitazone hydrochloride, which covers at least a part of a core containing a biguanide, wherein one or both of the core and the first layer is/are dispersed in a modulating release agent such as polysaccharides and the like, is reported (see, U.S. Pat. No. 6,403,121).